1. Field of the Invention
The present invention relates to a device for adjusting a space between chips in a semiconductor chip tester for testing performances of a semiconductor chip fabricated in a semiconductor process, in which a space between the chips is adjusted to suit to a pitch of a recesses in a position determining block when the chip put in a custom tray is adsorbed and transported toward the position determining block.
2. Discussion of the Related Art
In general, the custom tray of plastic having chips put therein for safekeeping or transportation between steps of chip fabrication is different in shape, size, capacity, pitch between recesses for putting the chips therein depending on manufacturers. Since the purpose of the recess in the custom tray is just putting in the chip, the space is formed without any high precision. However, the recess in a test tray for putting in the chip to be tested therein is formed with a high precision for making a perfect contact of the chip loaded in the test tray with a test connector (a connector for electrically connecting leads on the chip and the tester). Therefore, in order to make an accurate loading of the chip in the recess in the custom tray onto the recess in the test tray, a position determining block of a high accuracy should be used separately for accurate alignment of the chip position. To do this, the semiconductor chip tester is provided with a transportation means with a pick-up for transportation of chips. FIGS. 1 to 4 illustrate an art developed by the applicant and filed in Korea with an utility model application No. 95-7512. The aforementioned art will be explained with reference to FIGS. 1 to 4.
In the tester, there are a top plate 1 having a mounting plate 3 fitted thereto to be movable along a first horizontal LM guider 2 and a pick-up block 5 mounted under the mounting plate 3 for moving in up and down direction according to a movement of a first cylinder 4. And, there are a plurality of sliders 7 fitted to the pick-up block 5 each for moving along a second horizontal LM guider 6 in a direction the same with the direction of the mounting plate 3 movement, and each of the sliders 7 has a pick-up head 11 adapted to be guided by a vertical LM guider 9 in moving in an up and down direction according to a movement of a second cylinder 8. There is a pick-up 10 at a bottom of each of the pick-up heads 11 for adsorbing a chip 20 by a vacuum. As shown in FIGS. 3 and 4, there are pins 12 fixed to top of each slider 7 and exposed through a long hole 5a in top of the pick-up block 5, to make a hinge coupling with a first link 13 at a center thereof, each end of which first link 13 has a pin 15 connected to one end of a two pieced second link 14 for interlocked movement of the first, and second links 13 and 14. There is a guide piece 17 with a guide groove 17a for moving in a left and right direction according to a movement of a cylinder 16, and there is a projection 18 at one end of the first link at a middle of the first link inserted in the guide groove 17a.
The background art device for adjusting a space between chips having the aforementioned system starts operation in a condition when the pick-up 10 for adsorbing the chip 20 in the recess 19a of the custom tray 19 is at a top dead center and the slider 7 is drawn inwardly. When the mounting plate 3 moved along the first LM guider 2 comes to match with a first column of the recesses in the custom tray 19, movement of the slider 7 is stopped by a sensor. Under this condition, the first cylinder 4 fixed to the mounting plate 3 is driven to move the pick-up block 5 down to a bottom dead center, when the second cylinder 8 fixed to each slider 7 for moving the pick-up head 11 in an up and down direction is operated. According to this, the pick-up at one end of the pick-up head 11 moves downward as shown in one dotted chain lines in FIG. 2 until the pick-up makes contact with top of the chip 20 in the recess 19a of the custom tray 19. Then, the chip 20 in the recess 19a of the custom tray 19 is adsorbed to the pick-up 10 when a vacuum is established inside of the pick-up 10. While the chip 20 is adsorbed, the second cylinder 8 and the first cylinder 4 are operated in a sequence opposite to the aforementioned sequence, returning the pick-up head 11 and the pick-up block 5 to the top dead center the same as the initial state. Then, the mounting plate 3 is moved toward the position determining block along the first horizontal LM guider 2, when the third cylinder 16 fixed to top of the pick-up block 5 is driven to push the guide piece 17, moving the pin 18 fixed at one end of the first link 13 outwardly along the guide groove 17a in the guide piece as shown in FIG. 4. According to this, as shown in FIGS. 1 and 4, the first, and second links 13 and 14 drawn inwardly are opened outwardly until the pick-up is identical to a pitch of the recesses in the test tray. Under this condition, the first, and second cylinders 4 and 8 are driven in succession, to position the pick-up 10 down to the bottom dead center, positioning the chip adsorbed to the pick-up 10 in the recess of the position determining block (not shown). Upon releasing the vacuum in the pick-up, the chip at the pick-up is dropped into the recess of the position determining block, exactly. This background art device can shorten a time period of position determination by implementing operations of adsorbing one column of chips in the custom tray at a time, position determining by adjusting spaces between the chips during transportation toward the position determining block, and loading the chips of which positions are determined on the test tray by means of one transportation device. And, a space for installing the tester can be minimized.
However, though the pick-ups 10 at opposite sides of the tester can be positioned right over the recesses of the position determining block or the test tray exactly when the sliders 7 are fully drawn apart because the sliders 7 are interlocked with the plurality of the first, and second links 13 and 14, the pick-ups 10 between the opposite side pick-ups 10 can not be so because ends of the links can be positioned inaccurately due to flexibility of comparatively long lengths of the links. Due to this, there has been a fatal problem that the chips at ends of the pick-ups are loaded in the recesses of the position determining block, inaccurately. The complicated system with many components requires much machining and assembling time period.
In order to improve the aforementioned problems, an art illustrated in FIGS. 5 and 6 is developed again, and filed a utility model with an application number 96-22005 in Korea, which will be explained in detail.
There are a plurality of links 21 and 22 having first inserting holes 21a and 22a respectively, in each of which holes 21a and 22a a shaft 23 fixed to the slider 7 is inserted. The links 21 and 22 have second inserting holes 21b and 22b at the other ends respectively, in which holes 21b and 22b a pin 24 for interconnecting the links 21 and 22 are inserted. Accordingly, when the sliders 7 are drawn inward, that is, referring to FIG. 6a, when the pins 24 connecting the links 21 and 22 come closer to the shafts 23 fixed to the sliders 7, with the links crossed to each other, the plurality of sliders 7 can be packed together. Under this condition, when the mounting plate 3 is moved to be matched with one column of recesses of the custom tray, the first cylinder 4 fixed to the mounting plate 3 is driven, moving the pick-up block 5 down to the bottom dead center. On the same time, the second cylinder 8 is driven, moving the pick-up head 11 downward until the pick-up 10 at an end thereof is brought into contact with top of the chip 20 in the recess 19a of the custom tray 19, when the pick-up adsorbs the chip 20 by a vacuum. When the chip 20 is adsorbed to the pick-up 10 in the aforementioned operation, the second cylinder 8 and the first cylinder 4 are driven in succession opposite to the aforementioned operation, elevating the pick-up head 11 and the pick-up block 5 upward the same as the initial stage, respectively. On the same time with this, the mounting plate 3 is moved toward the position determining block along the first horizontal LM guider 2, when the third cylinder 16 is driven, pushing the guide piece 17 to draw the links 21 and 22 apart. According to this, the sliders 7 fixed to the links 21 and 22 are also drawn apart, with the chips adsorbed to the pick-ups 10 matched with the recesses of the position determining block. In the foregoing operation, as shown in FIG. 6b, since the pins 24 connecting the links 21 and 22 come closer to the shafts 23 fixed to the sliders 7, spaces between the plurality of sliders 7 can be constant. Since this system has the shaft 23 fixed the slider 7 closer to the pin 24 connecting the links 21 and 22, distances between the pick-ups 10 can be maintained constant.
However, because this second exemplary background art device has a number of components greater than the first exemplary background art device, an exact pitch can not be obtained due to a cumulative tolerance in fabrication and assembly. The errors between pick-ups becoming serious from wear of links and bearings in a prolonged use of the device has been a cause of noise.